computer-bios endless reboot cycle

I am fixing a PC up and am having some problems defining the problem. The PC worked fine for my father for a couple years and recently it stopped working. The case fan and cpu fan would turn on, but the monitor would be black. The first step I took was I replaced the old AM2 CPU with a slightly faster one. The problem still persisted. I went out and swapped for a new motherboard. The old one was an ECS. The new one is the same model made by FOXCONN (M61PMV). The computer still had the same problems. I changed the old hard drive with a refurb WD 500GB SATA. The computer would turn on now, but after trying to install Windows 7, it would finish copying the files over and it would keep rebooting. Now the computer takes a solid few minutes to post after I hit the power switch and within 5 minutes of it turning on it will reboot by itself. I've cleared the cmos with jumpers as well as the battery and holding down the power switch for 30 secs. It still will automatically reboot within a few minutes of turning on. I've switched both sticks of ram for an older set that I had, yet it still would do the same thing. I've swapped the power supply and cannot figure out the problem. The only constant would be the case itself, the DVD drive, and the case fan.

I tried to do the memtest via Windows 7 Diagnostic Tools. This is a fresh install. Does this have anything to do with the Master boot record? I've tried turning on the system without the HDD or DVD drive attached power and cords. I'm using on board graphics.

If your mboard is not new (usually the mboard is at least 2 years old when this happens)......

Some mboards develop this problem - electrolytic capacitors were installed on them that were not properly made, and they fail eventually - the mboard manufacturer didn't know they were improperly made at the time the mboard was made.

Open up your case and examine the mboard to see if you have bad capacitors, and/or other findable signs of mboard damage .

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